The disclosure relates to a developing cartridge, an image holding body cartridge, a process cartridge, and an image forming apparatus.
In an image forming apparatus to which a developing cartridge having a rotatable developing roller is attached, a bias voltage is applied to the developing roller from a power supply electrode connected with an electric circuit provided to a body of the image forming apparatus. The bias voltage is applied in a state where the developing cartridge is attached to the image forming apparatus. U.S. Pat. No. 6,823,160 discloses such a structure (FIG. 8A in the patent). In this structure, an electrical supply member is integrally provided to an extended portion of a roller shaft of the developing roller in an axial direction of the roller shaft. An electrode plate, as the power supply electrode, is arranged so as to press an end surface of the electrical supply member in the axial direction. With this structure, the electrical supply member and the electrode plate are electrically connected with each other so that a bias voltage is applied to the developing roller.
The developing roller develops an image by adhering a developing agent to a latent image which is formed on the surface of a photosensitive drum. In order to increase development accuracy, the developing roller needs to contact the photosensitive drum with a uniform pressure along a length of the photosensitive drum in an axial direction of the photosensitive drum.